The Food and Drug Administration (FDA) has authorized emergency use of a new test for coronavirus antibodies that could be a key part of a broader strategy to help Americans resume a more normal life.

The pinprick blood test by North Carolina-based Cellex is similar to some already in use in Asia and Europe. These tests are not intended to replace tests based on swab specimens that can detect an early, active case of the COVID-19 disease. But they could be a vital complement, helping to identify people who have developed protective antibodies after being exposed to the virus and who might be able to venture from their homes with less risk.

“I think this is a very important next step,” said Dr. John Scott, pharmacology chair of the University of Washington’s School of Medicine. “It tells you the people who have been infected and been able to mount an immune response against the virus.”

In Washington, state officials say their focus, so far, is on expanding the swab-based tests. They have yet to offer a public plan for how or when blood-based testing could be rolled out.

But asked earlier this week about developments for antibody testing in Washington, state epidemiologist Dr. Scott Lindquist told The Seattle Times by email “we are part of a CDC seroprevalence study to begin any day.” He declined to provide further details.

A public-information officer said that such studies general involve “checking for antibody levels” but that this study was so preliminary that no further details could be provided.

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In recent weeks, the state Department of Health has also been pressed by state Sen. Lynda Wilson, R-Vancouver, to take a closer look at 100 antibody test kits she received from a Michigan-based company. So far, she says she has not had much success.

I am frustrated,” Wilson said. “We won’t know how this virus has expanded in our state until we get antibody tests done.”

There also is interest in the antibody tests in the Puget Sound region. Seattle and King County’s health officer for public health, Jeffrey Duchin, said the antibody testing would be “very valuable in understanding the potential for disease transmission going forward.” But under all the strains of the pandemic, he said the logistics of deploying it on a big scale would be daunting.

Even without government guidance, some state hospitals or clinics could opt to obtain blood-based tests directly from suppliers as they become more available.

Some of these blood tests can be completed in 15 minutes or less without using special instruments, according to statements from suppliers.

In a patient who contracted the virus, the results may indicate the presence of an antibody called IgM that typically develops within 10 days of exposure and signals an active infection. They also may detect a secondary antibody, IgG, which indicates that a patient has a later phase of COVID-19 disease, or has recovered.

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These tests could detect people who are largely without symptoms or came down with a mild fever, dry cough or shortness of breath and never got a swab test.

“I think it would help a lot of people — it would be great,” said Jessica, a Seattle tech worker who got sick in early March with COVID 19-like symptoms, self-isolated and tried unsuccessfully to get a swab test from a clinic. Out of concerns for privacy, she requested that The Seattle Times only identify her by her first name.

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For researchers, scrambling to better understand the COVID-19 disease, there still is no clear answer on just what level of protection people who possess the antibodies can expect in a world gripped by the pandemic.

Dr. Andrew Fauci, director of the National Institute for Allergy and Infectious Diseases, said the protection gained from such exposure is never 100 percent. But a small study in China on primates indicated monkeys did gain some immunity. And in an interview with Trevor Noah of The Daily Show, Fauci said “I feel really confident that if this virus acts like every other virus that we know, once you get infected, get better, clear the virus … you’ll have immunity that will protect you against the infection.”

In recent weeks, the United Kingdom has launched one of the most aggressive efforts to put these tests into use. The government ordered some 3.5 million tests that will be reviewed by the government officials for accuracy and then made available to the public through Amazon, according to a March 25 report by The Guardian.

In the United States, the tests could be a screening tool to help hospitals, nursing homes and businesses. Earlier this week, 113 members of the House of Representatives sent a letter to the Trump Administration calling for them to be “rapidly deployed to all America, so that people who have acquired COVID-19 immunity can re-enter the work force and restart the economy.”

U.S. regulation of these tests is still very much a work in progress.

In a March 16 statement, the FDA, citing the need to expand both the capacity and the kinds of diagnostic tests, did not object to their use as long as the companies providing them applied for emergency regulatory approvals and they were not the sole basis for diagnosis.

Since then, the FDA has authorized emergency use of the Cellex antibody test for use by authorized laboratories. But an agency letter dated April 1 noted that all advertising and descriptive material must “clearly and conspicuously state” that the test has not been FDA cleared or approved.

Others U.S. firms, while seeking such authorizations, have begun to offer the blood-based tests, many of which are imported from China or other Asian countries. New York-based Henry Schein, a major medical supplier, anticipated by the end of March acquiring several hundred thousand tests developed by South Korea-based S.D. Biosensor, with more on the way in April.

“We are working through multiple channels to distribute the tests to health care professionals,” Henry Schein said in a statement to The Seattle Times that did not provide any details on whether sales included any Washington hospitals or clinics.

Another company, United Biomedical, has donated tests kits to San Miguel County in Colorado in an effort now underway to screen all residents there for the coronavirus antibodies.

Michigan-based Air Force Inc. provided kits imported from China to Wilson to help spur interest in Washington state in the tests.

Meanwhile, the U.S. Centers for Disease and Prevention has been developing its own blood test that could help to determine how much of the U.S. population has been exposed to COVID-19, including people who had few or no symptoms. And in New York, Gov. Andrew Cuomo announced last week that the state Department of Health would work with private hospitals to develop antibody testing.

“This could be a big breakthrough,” Cuomo said.

Seattle Times staff reporter Sandi Doughton contributed to this report.